CN111418110B

CN111418110B - Lithium ion battery recycling method

Info

Publication number: CN111418110B
Application number: CN201880062168.1A
Authority: CN
Inventors: 多米尼克·莫林; 查尔斯·加涅-布尔克; 埃米莉·纳多; 贝努瓦·库图尔
Original assignee: Lithium Ion Recycling Co
Current assignee: Lithium Ion Recycling Co
Priority date: 2017-09-28
Filing date: 2018-09-27
Publication date: 2023-10-13
Anticipated expiration: 2038-09-27
Also published as: EP3688834A4; WO2019060996A1; EP3688834A1; CN111418110A; CA3076688C; JP7253538B2; JP2020535323A; US11508999B2; KR20200060464A; US20210376399A1; CA3076688A1

Abstract

There is provided a method of recovering a lithium ion battery, comprising: cutting up the lithium ion battery, and immersing the residue in an organic solvent; feeding the chopped cell residue into a dryer to produce a gaseous organic phase and a dried cell residue; feeding the dried battery residue to a magnetic separator to remove magnetic particles; grinding the non-magnetic battery residue; mixing the fine particles with an acid to produce a metal oxide slurry and leaching the metal oxide slurry; filtering the leachate to remove non-leachable metals; feeding the leachate to a sulphide precipitation tank; neutralizing the leaching solution; mixing the leaching solution with an organic extraction solvent; separating cobalt and manganese from the leachate using solvent extraction and electrolysis; crystallizing sodium sulfate from the aqueous phase; adding sodium carbonate to the liquid and heating the sodium carbonate and the liquid to produce a lithium carbonate precipitate; and drying and recovering the lithium carbonate.

Description

Lithium ion battery recycling method

Technical Field

A method of recycling a lithium ion battery is provided.

Background

Today, most lithium ion battery recycling methods have a huge environmental footprint (footprint) and cannot recover many valuable materials. Materials used to fabricate lithium ion batteries (e.g., lithium and cobalt) are expected to be a threat in the near future, and alternative sources of these materials must be used to ensure that the cost of the lithium ion battery is affordable. Recovery is also indispensable in order to obtain positive environmental impact using electric vehicles, because raw material exploitation of the battery assembly has a great environmental burden.

Some battery recyclers focus on the mechanical and physical separation of the various components of the battery after breakage, such as the housing, current collector, and electrode materials. These processes typically involve breaking the cell under a controlled inert atmosphere. The crushed material is then separated by sieving, air and magnetic separation and sent to other facilities for further processing. These types hardly provide a way to produce value added components and are mainly used to eliminate the environmental impact of disposing of the whole waste battery.

A pyrometallurgical process (prymetallurgical) may be used to separate the different elements of the spent lithium ion battery. The assembly is burned by heating the organics and polymer at high temperature. Heavier metals (e.g., cobalt, copper, and nickel) are melted into alloys, and other elements eventually become slag. The metal alloy is sold to metal smelters for separation. Importantly, lithium is lost to the slag of these processes and cannot be recovered and sold. The alloys sold account for a portion of the value of the separated pure metal.

Hydrometallurgical processes (hydrometallurgical) are typically used after mechanical treatment to separate and purify the different metals contained in the cathode. These processes typically include a leaching step to dissolve the metal oxide into an aqueous solution, and various precipitation and separation steps to obtain a relatively pure metal. These types of processes are still under development and are expensive to operate due to steps such as liquid nitrogen immersion or the use of large amounts of chemical chemicals. In addition, there is generally little consideration in treating liquid waste.

There is currently no large-scale industrial process that can handle an ever-increasing number of spent lithium ion batteries. Even smaller pilot plants are still in the development stage and cannot handle all the different battery compositions and purify the value-added elements in an economical way.

Accordingly, there remains a need to provide a method that can economically handle all types of spent lithium ion batteries.

Disclosure of Invention

According to the present disclosure, there is provided a method of recovering a lithium ion battery, comprising the steps of: shredding the lithium ion battery, immersing the residue in an organic solvent to safely discharge the battery, and producing shredded battery residue and a liquid comprising an organic compound and lithium hexafluorophosphate; feeding the chopped cell residue into a dryer to produce a gaseous organic phase and a dried cell residue; feeding dry battery residue comprising magnetic and non-magnetic battery residue to a magnetic separator, removing magnetic particles from the dry battery residue; grinding the non-magnetic battery residue to a particle size of about 0.1-10 millimeters, the resulting particle size distribution comprising fine particles in the upper range (including plastics) and in the middle-low range, comprising aluminum, copper, metal, and graphite; mixing the fine particles with an acid to produce a slurry, and leaching the metal oxide slurry to produce a leachate (leache) comprising metal sulfate and non-leachable materials; filtering the leachate to remove non-leachable materials from the leachate; feeding the leachate into a sulphide precipitation tank, removing ionic copper impurities from the leachate; neutralizing the leachate at a pH of 3.5 to 5 to remove remaining iron and aluminum from the leachate; mixing the leachate with an organic extraction solvent to produce an aqueous phase comprising lithium, sodium and nickel, and an organic phase comprising cobalt, manganese and the remainder nickel; crystallizing sodium sulfate from the aqueous phase containing lithium to produce a liquid containing lithium and sodium sulfate crystals; adding sodium carbonate to the liquid and heating the sodium carbonate and the liquid to produce a lithium carbonate precipitate; and drying and recovering the lithium carbonate.

In one embodiment, the organic solvent is an aliphatic carbonate.

In a further embodiment, the organic solvent is maintained at a temperature of less than 40 ℃.

In another embodiment, the catalyst is used under an inert atmosphere (e.g., using but not limited to nitrogen or CO ₂ ) The lithium ion battery is cut to a particle size of about 5-10 mm.

In another embodiment, the shredded battery residue is separated from the liquid by sieving or filtering.

In another embodiment, the methods described herein further comprise evaporating the liquid in an evaporator to produce a slurry and a condensate of the light organics.

In another embodiment, the methods described herein comprise separating dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC) and Ethylene Carbonate (EC) from the condensate of the light organics.

In one embodiment, the liquid is evaporated at a temperature of 90 ℃ to 126 ℃.

In another embodiment, the slurry is combusted at a temperature of about 500 ℃ to produce a slurry comprising hydrofluoric acid (HF) and phosphorus pentoxide (P ₂ O ₅ ) Is a combustion gas of (a) a combustion gas of (b).

In another embodiment, the HF is further removed in a fluidized bed reactor and P is neutralized in a wet scrubber ₂ O ₅ To form sodium phosphate (Na ₃ PO ₄ )。

In one embodiment, the shredded battery residue is dried at a temperature of 200-300 ℃.

In one embodiment, the non-magnetic battery residue is ground in a hammer mill or impact crusher.

In one embodiment, the methods described herein further comprise extracting aluminum and copper from the milled non-magnetic cells with an eddy current separator (eddy current separator).

In another embodiment, the aluminum and copper are further separated.

In one embodiment, the fine particles are mixed with sulfuric acid and water.

In a further embodiment, the fine particles and the acid are mixed to produce a metal oxide slurry having a solids concentration of 75 to 125kg solids per cubic meter of acid solution.

In another embodiment, the methods described herein further comprise adding a reducing agent to the metal oxide slurry for leaching.

In one embodiment, the reducing agent is hydrogen peroxide (H ₂ O ₂ ) Manganese oxide (MnO) ₂ ) At least one of aluminum powder (Al) and combinations thereof.

In another embodiment, the methods described herein further comprise purifying graphite from the non-leachable material in a furnace.

In one embodiment, the furnace is operated at a temperature of about 200 to 800 ℃.

In one embodiment, the methods described herein further comprise precipitating the ionic copper impurities by precipitation with sulfur ions (sulfide ions).

In further embodiments, the methods described herein further comprise precipitating aluminum and iron impurities by increasing the pH of the aqueous solution.

In another embodiment, the methods described herein further comprise mixing the leachate and the organic extraction solvent in a diluent.

In a further embodiment, the diluent is a petroleum-based reagent (petroleum-based reagent).

In one embodiment, the methods described herein further comprise washing and stripping the organic phase to extract cobalt and manganese.

In another embodiment, cobalt and manganese are separated by electrolytic deposition (electrowinning).

In another embodiment, the methods described herein further comprise increasing the pH of the aqueous phase to a pH of 10 to 12 to remove nickel sulfate (NiSO ₄ ) Nickel hydroxide (Ni (OH) ₂ ) And precipitating out.

In one embodiment, the aqueous phase is cooled at a temperature between about 0 ℃ and 10 ℃ prior to crystallization.

In another embodiment, the methods described herein further comprise electrolyzing the sodium sulfate crystals to produce sulfuric acid and sodium hydroxide.

In one embodiment, the catalyst is prepared by adding sodium carbonate or bubbling CO ₂ The gas adds carbonate ionsAdded to the liquid.

In a further embodiment, the lithium ion battery is a battery pack.

In another embodiment, the lithium ion battery is an automotive battery.

Drawings

Reference will now be made to the accompanying drawings.

Fig. 1 schematically illustrates an organic separation step of a method contemplated herein and according to one embodiment.

Fig. 2 schematically illustrates an electro-mechanical separation step of a method contemplated herein and according to one embodiment.

Fig. 3 schematically illustrates hydrometallurgical treatment steps of the methods contemplated herein according to one embodiment.

Fig. 4 schematically illustrates a plurality of metal separation steps after the solvent extraction steps contemplated herein according to one embodiment.

It should be noted that throughout the appended drawings, like features are identified by like reference numerals.

Detailed Description

According to the present description, a method of recycling lithium ion batteries is provided.

The present disclosure provides a method of recovering a lithium ion battery, comprising the steps of: shredding the lithium ion battery, immersing the residue in an organic solvent to safely discharge the battery, and producing shredded battery residue and a liquid comprising an organic compound and lithium hexafluorophosphate; feeding the chopped cell residue into a dryer to produce a gaseous organic phase and a dried cell residue; feeding dry battery residue comprising magnetic and non-magnetic battery residue to a magnetic separator, removing magnetic particles from the dry battery residue; grinding the non-magnetic battery residue, the resulting particle size distribution comprising fine particles in the upper range (including plastics) and in the middle and low ranges, comprising aluminum, copper, metal and graphite; mixing the fine particles with an acid to produce a slurry and leaching the metal oxide slurry to produce a leachate comprising metal sulfate and non-leachable materials; filtering the leachate to remove non-leachable materials from the leachate; feeding the leachate into a sulphide precipitation tank, removing ionic copper impurities from the leachate; neutralizing the leachate at a pH of 3.5 to 5 to remove remaining iron and aluminum from the leachate; mixing the leachate with an organic extraction solvent to produce an aqueous phase comprising lithium, sodium and nickel, and an organic phase comprising cobalt, manganese and the remainder nickel; crystallizing sodium sulfate from the aqueous phase containing lithium to produce a liquid containing lithium and sodium sulfate crystals; adding sodium carbonate to the liquid and heating the sodium carbonate and the liquid to produce a lithium carbonate precipitate; and drying and recovering the lithium carbonate.

The method described herein is designed to be able to handle all cathode compositions of commercially available lithium ion batteries. The methods described herein may be implemented in a factory that can also handle all forms of battery packs, including plastic housings and brackets, to limit manual disassembly.

Waste batteries entering the end of their useful life may have different compositions. The cathode is typically made of lithium metal oxide, with the metal portion made of a mixture of cobalt, nickel and manganese. Other cathode compositions, such as lithium iron phosphate, may also be processed. The anode is typically made of graphite, but may also consist of metallic lithium. The electrolyte may be a liquid solvent, typically a mixture of aliphatic and cyclic carbonates with dissolved lithium salts, or may be a solid, such as a lithium-based solid electrolyte.

Organic separation

As shown in fig. 1, the method comprises a first step of: the spent cells of the receptacle 1 are chopped 2 to safely discharge and expose the internal components of the cells to downstream electrolyte extraction. In one embodiment, shredding is completed to a target particle size of about 5 to 10 millimeters.

There may be an electrical charge in the spent battery. If the internal components of the rechargeable battery are exposed to moisture in the ambient air, an exothermic reaction occurs, generating hydrogen gas. This entails a serious risk of hydrogen combustion. In order to minimize the risk of combustion, the whole waste batteries are chopped and then immersed in an organic solvent. The organic solvent is used for dissolving and extracting electrolyte salt contained in the battery, such as hexafluorophosphateLithium acid (LiPF) ₆ ). Which is miscible with the electrolyte solvent present in the battery, preferably an aliphatic carbonate. Thus, contact between the cell internal components and oxygen is thereby limited. In addition, in the case of exothermic reactions, the organic solvent will act as a heat sink (heat sink), thereby reducing the operational risk. In one embodiment, the organic solvent is maintained below 40 ℃ by circulating the solvent through a heat exchanger or using a jacket around the container housing the chopped cells.

After chopping 2, the particles or chopped cell residues, and solvent are subjected to an extraction step to ensure good washing of the electrolyte salt. The extractant is the same as the solvent used in the shredding step 2. In one embodiment, the extraction is performed at a temperature of 40 ℃ to 60 ℃ with a residence time of 30 minutes to one half hour, at a test operating point of 50 ℃ for 1 hour. This step may be accomplished in any typical heating and mixing tank unit. The chopped cell residue or particles are then separated from the liquid by sieving or filtration.

The liquid phase containing the organic solvent is fed to an evaporator 3 operating at the boiling point of the solvent mixture, which may vary from, for example, 90 ℃ for pure dimethyl carbonate to, for example, up to 126 ℃ for pure diethyl carbonate. A typical operating point for the electrolyte salt and solvent mixture is expected to be about 90 ℃ at atmospheric pressure. The lighter molecules of the organic phase (mainly the solvent used upstream) will be evaporated and condensed. The heavier organic molecules, still containing electrolyte salts from the spent cells, will remain in slurry form at the bottom of the evaporator.

The condensate of the majority of the light organics can be returned to the shredding step 2 and another portion corresponding to the accumulation of organic solvent is discharged to the separation step 4 to purify the different molecules in the light organic phase. The light organic phase is composed of organic carbonate compounds such as, but not limited to, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate. In one embodiment, three distillation columns are used. The first column 4a is operated at about 90 ℃ to obtain battery grade dimethyl carbonate (DMC) in the overhead. The second column 4b is fed as the bottom of the first column. It contains methyl ethyl carbonate (EMC), diethyl carbonate (DEC) and Ethylene Carbonate (EC). The second column was operated at about 107 ℃ to obtain battery grade Ethyl Methyl Carbonate (EMC) in the overhead. The second bottom is fed to the third column 4c and operated at about 126 ℃ to obtain battery grade diethyl carbonate (DEC) in the overhead and technical grade Ethylene Carbonate (EC) from the bottom.

The wet battery residue is fed to a dryer 7 operated at 200 to 300 ℃ to remove the organic solvent in the residue. The gas phase containing the majority of the light organics will be sent to the first solvent evaporation 3 outlet. The battery residue from the dryer outlet 7 is fed to a magnetic separator 11.

The heavy organic slurry from evaporator 3 is burned 8 at a temperature of about 500 c to eliminate toxic organic fluorophosphate molecules and remove all reactive fluoride from the process. The combustion gas will contain hydrofluoric acid (HF) and phosphorus pentoxide (P) ₂ O ₅ ) The method comprises the steps of carrying out a first treatment on the surface of the These molecules are highly reactive and require treatment prior to delivery to the environment. HF is removed by a dry wash 9, such as, but not limited to, a dry lime scrubber or a catalytic alumina dry scrubber, where any aluminum plant can safely dispose of the waste as part of its feed product. Neutralization of P in wet scrubber 10 using caustic solution ₂ O ₅ Forms environmentally friendly waste products, such as sodium phosphate (Na ₃ PO ₄ )。

Electro-mechanical separation

The battery residue is fed from the dryer outlet 7 to a magnetic separator 11 to separate the iron flakes and particles lifted onto the magnets from other solids.

The non-magnetic battery residue is subjected to a comminution step 12 or the average particle size is reduced to a smaller average particle size, to a particle size between 0.1 and 2 mm. Different crushing and pulverizing unit operations may be used, such as, but not limited to, a hammer mill or an impact crusher. The plastic will form the upper range of the particle size distribution. The aluminum foil and copper foil will be crushed into a strip form. The metal in the cathode and the graphite in the anode will be crushed and form the lower range of the particle size distribution.

In one embodiment, the crusher output is then screened 13 at about 1 mm. The oversized fraction is fed to a second grinding and sieving step 14 using, for example, but not limited to, a high shear mixer or equipment such as a chopper to remove residual anode and cathode materials adhering to the aluminum and copper foil. After a second screening with the same size (-1 mm), the fine particles of step 14 are sent to be mixed with the fine particles from the previous screening 13.

Coarse particles mainly containing plastic, copper and aluminum are then fed into the vortex separator 15, where aluminum foil and copper foil are extracted. The remaining plastic may be sent to a recycling station. The aluminum foil and copper foil are then separated by density classification 16 using equipment such as, but not limited to, an air classifier.

Hydrometallurgical treatment

In the leaching tank 17, the fine particles from the screening unit are mixed with sulfuric acid and water to obtain a metal oxide slurry having an acidic mass concentration of 10 to 30% in the liquid phase of the slurry, the operating point of which is about 17%. For solids concentrations of 75 to 125kg solids per cubic meter of acid solution, mixing requires 1 to 4 hours at about ambient temperature. Typical operation should be at 100kg/m ³ Is carried out at-20℃for 3 hours.

A reducing agent may also be added to the reaction tank to aid in leaching the transition metal, such as, but not limited to, hydrogen peroxide (H) ₂ O ₂ ) Manganese oxide (MnO) ₂ ) Or aluminum powder (Al). Typical working concentration of reducing agent for H ₂ O ₂ May be 0 to 30% w/w of the solution for MnO ₂ May be 0 to 5% w/w and may be 0 to 5% w/w for Al. The transition metals (Co, ni, mn) in the slurry are reduced or oxidized to a divalent (2+) oxidation state where they can leach more easily. Leaching of the metal oxide slurry produces a leachate of metal sulfate, which is filtered out of the solid non-leachable material.

As shown in fig. 3, graphite and other non-leachable elements are filtered out 18 and sent to graphite purification. Will contain sulfate (Li) ₂ SO ₄ 、CoSO ₄ 、NiSO ₄ 、MnSO ₄ 、Fe ₂ (SO ₄ ) ₃ 、Al ₂ (SO ₄ ) ₃ 、CuSO ₄ ) The filtrate in the form of lithium, cobalt, nickel, manganese, iron, aluminum and copper is sent to sulphide precipitation 21.

After filtration, the resulting graphite cake is suspended 19 back in a liquid similar to the aqueous solution from the leaching step. Which is also sulfuric acid with a reducing agent (such as, but not limited to hydrogen peroxide (H) ₂ O ₂ ) Manganese dioxide (MnO) ₂ ) Or aluminum powder (Al)) using the same composition ranges as before. The solution may dissolve the remaining metals in the graphite. The graphite was then filtered and thoroughly washed with water. The graphite cake is then fed into a furnace 20 operating at 200 to 800 ℃ (preferably 600 ℃) to evaporate the remaining plastic and dry the graphite.

The leachate is sent to a sulphide precipitation tank 21 to remove ionic copper from the solution, which is derived from the leached metallic copper that remains after vortex separation. Copper impurities can be removed by reaction with sulfur ions (S ^- ) Binding and precipitating. The source of the sulfide ion may be any sulfide ion compound such as, but not limited to, sodium sulfide (Na ₂ S) or bubbling hydrogen sulfide (H) ₂ S). At a pH below 2 and a temperature of 40 to 80 ℃, the sulfide will selectively combine with copper to form water insoluble copper sulfide (CuS). Depending on the concentration of copper ions in the solution, na ₂ The concentration of S may be 2 to 5kg Na ₂ S per kg of leached battery residue and a holding time of 30 minutes to 1 hour. The precipitate is removed from the main process by filtration and sold.

The leachate is then neutralised 22 to a pH of 3.5 to 5.0 by the addition of sodium hydroxide (NaOH) to precipitate the remaining iron and aluminium, which will form a water insoluble hydroxide (Al (OH) ₃ 、Fe(OH) ₃ ). Precipitation took 30 minutes to 2 hours to stabilize, and the reaction time was expected to be 1 hour. The precipitate is filtered off from the process.

Final metal separation

The leachate is mixed with an organic extraction solvent (extractant) dissolved in a petroleum-based reagent (diluent) 23. The concentration of extractant in the diluent may vary between 2 and 10 mass percent, with values between 4 and 6 being more typical. When the pH of the aqueous solution is between 4.5 and 7, the divalent transition metals (Co, mn, ni) will be extracted by the organic phase, while lithium and sodium will remain in the aqueous phase. If the pH is kept at a value between 5.4 and 6.2, nickel will only be partially extracted. This pH range is used to separate nickel from cobalt and manganese.

For the solvent extraction process, a mixer-settler, an extraction column (e.g., a pulse column, a column with internal stirring by a rotating impeller, a reciprocating plate extraction column), a hollow fiber membrane, etc. can be used. For the above-described apparatus, the lighter organic phase is typically pumped out of the top of the buffer zone (where it is no longer mixed) and the heavier aqueous phase flows out of the bottom of the apparatus, through another buffer zone where there is sufficient time to separate by decantation. The organic phase is then sent to the washing and stripping stage and the aqueous phase (raffinate) is sent to further precipitation steps.

In the washing stage 24, the organic phase is contacted with an aqueous solution having a high concentration of cobalt and manganese to selectively strip nickel from the organic phase. The wash solution is part of a (Co, mn) rich stripping solution, the pH being adjusted to 3 to 4 with sodium hydroxide. The two phases are mixed and separated in a device similar to that previously described. Returns to the aqueous solution and mixes with the solvent extraction inlet.

In the stripping stage 25, the organic phase is contacted with an aqueous solution containing sulfuric acid at a pH of 1 to 2 to strip the cobalt and manganese together. Again, a device similar to that described previously was used here to mix and separate the two phases. The clean organic solvent is then returned to the extraction stage and the now (Co, mn) rich aqueous phase is separated between the wash stage 24 and the cobalt electrowinning step 26.

Cobalt and manganese must be separated from each other. If neutralized with sodium hydroxide, they precipitate together, but because they have different standard reduction potentials (cobalt-0.28V and manganese-1.18V), they can be separated by the electrowinning process 26. Cobalt will plate onto the cathode in its metallic form and then be scraped off. Manganese will be oxidized to MnO ₂ And deposited on the anode. Using undivided cells with cobalt blank cathode (cobalt blank cathode) and DSA anode, using 150 to 350A/m ² Is subjected to cobalt electrowinning at a current density and a voltage of 2.7 to 5V. The electrolyte is fed at a temperature of 45 to 70 ℃ at a pH of 2.5 to 5. The spent electrolyte is returned to the stripping step 25 as stripping solution. The electrode reactions were as follows:

and (3) cathode:

anode:

after the solvent extraction step, the aqueous raffinate contains a large amount of dissolved nickel sulfate (NiSO ₄ ). The pH of the solution was raised to 10 to 12, with the expected value of 10.8, by adding sodium hydroxide 27, to precipitate nickel hydroxide (Ni (OH) ₂ ). Precipitation took 30 minutes to 2 hours to stabilize, and the reaction time was expected to be 1 hour. The nickel hydroxide is filtered, washed and dried 28 for sale.

At this point in the process, the remaining aqueous solution contains a significant proportion of sodium sulfate (Na ₂ SO ₄ ). Sodium sulfate is produced by neutralizing sulfuric acid with sodium hydroxide that occurs during hydroxide precipitation. The high concentration of sodium sulfate, combined with its important dependence of solubility on temperature, makes it extremely suitable for surface cooling crystallization 29. By cooling the neutralized leachate to 0 to 10 ℃, most of the sodium sulfate will crystallize into decahydrate crystals, known as Glauber salt (Na ₂ SO ₄ *10H ₂ O). Removal of sodium sulfate in hydrated crystal form also has the benefit of concentrating the remaining lithium in the aqueous solution (mother liquor). The crystals produced are fed into a centrifuge for dewatering and washing.

The sodium sulfate crystals produced will have a higher purity level due to the number of purification steps upstream. The lack of contamination enables electrolysis 30 because only a few parts per million of multivalent metal ions in solution will cause precipitation in the cell membrane. Electrolysis of sodium sulfate will produce sulfuric acid at the anode and sodium hydroxide at the cathode, which is the primary consumable reagent required for the process. This step would eliminate the need to feed fresh sulfuric acid and sodium hydroxide into the process. For this type of process, 25 ℃ and Na for constant bath temperature ₂ SO ₄ 15 to 25% by mass of feed material, the current density may be 1 to 3kA/m ² While the corresponding voltage may be 5 to 20V. The expected operating value should be a current density of 1kA/m ² At a voltage of 10V, feed Na ₂ SO ₄ The mass percentage is about 18%. The electrode reactions were as follows:

and (3) cathode:

anode:

the mother liquor coming out of the crystallizer is heated to a temperature between 80 and 100 ℃ and a source of carbonate ions (CO ₃ ^2- ) Added to the aqueous solution. The carbonate ion source may be a carbonate ion compound, such as sodium carbonate (Na ₂ CO ₃ ) Or by bubbling CO ₂ Gas to generate carbonate ions (HCO) ₃ ^- ). The carbonate ion reacts with lithium ion to produce lithium carbonate (Li) ₂ CO ₃ ) 31, which is slightly soluble in water. Precipitation was expected to take 30 minutes to 2 hours to stabilize, with an operation hold time of 1 hour. The precipitate is filtered and dried 32 and sold as dried lithium carbonate.

The remaining aqueous solution is recycled back to the primary leaching zone to prevent lithium from being sent to water treatment.

Example I

All of the processes of the battery recycling methods described in the examples below were performed continuously on a laboratory scale. They include shredding, grinding, sieving, electrolyte solvent extraction, leaching, precipitation (sulfide, hydroxide and carbonation), solvent extraction, electrowinning and crystallization. First, the cells were roughly chopped, and the electrolyte solvent was recovered by evaporation. The chopped solids are then finely ground and then sievedAnd magnetizing to remove plastics and iron respectively and leaching. Na is mixed with ₂ S is added to the leachate to obtain sulfide precipitate, and then the pH of the resulting leachate is raised to obtain hydroxide precipitate. The leachate is then contacted with an organic solvent. This organic solvent is then washed, stripped and finally transferred to an electrowinning cell. The pH of the aqueous solution was again increased to obtain nickel hydroxide. Thereafter, the temperature is lowered to remove sodium, and then raised to effect carbonation precipitation.

First, about 150g of the battery was chopped, immersed in a dimethyl carbonate solvent, and heated at 110 ℃ in a flask. After filtration, the lithium salt was recovered by distillation of the solvent (LiPF ₆ ). The chopped cells were then ground to 0.1-2mm portions and ready for leaching.

Leaching requires 2 mol/L98% concentrated sulfuric acid and 1.6mL hydrogen peroxide per gram of metal powder. The leaching time may take up to 4 hours. The residue was washed with distilled water and filtered.

After filtration, the next step is sulfur precipitation to remove copper. 10wt% sodium sulfide with respect to the metal powder was added to the leachate to precipitate copper sulfide (CuS). It is then washed and filtered. The reaction takes at least 30 minutes to complete.

Then, after filtration, about 40g of sodium hydroxide was added to the leachate to obtain pH 0 to 5.5, to obtain iron and aluminum hydroxide precipitate. Due to the gelatinous nature of ferric hydroxide, hydroxide precipitation is difficult to filter. The amount of NaOH was used for 50g of metal powder with 2mol/L H ₂ SO ₄ . The precipitate was washed and filtered.

The leachate was then contacted with a rare machine solvent, which was a mixture of 10v.% cyanex 272 and 90v.% naphtha (nappta), the ratio of organic leachate being 1:1. The aqueous phase is rich in nickel and lithium. The organic phase is washed and stripped to recover cobalt and manganese. It is recycled to the initial operation of solvent extraction.

The cobalt and manganese concentrate solutions were set to a pH of 3.5 and then transferred to an electrowinning cell with an applied current density of about 200A/m ² . After one hour of electrolytic deposition at 50 ℃, metallic cobalt is plated on the iron cathode, and manganese dioxideDeposited on the lead anode.

The pH of the aqueous phase rich in nickel and lithium after extraction by a solvent was raised to 10.8 to obtain nickel hydroxide precipitate. It was filtered and washed.

The pH of the aqueous phase was adjusted to 8. Then cooled to 5 ℃ for 30 minutes in an ice bucket to extract sodium sulfate. It was filtered and washed.

The aqueous phase was then heated to 90 ℃, sodium carbonate was added to carry out the carbonation reaction and form lithium carbonate. The precipitate was filtered and washed. The reaction was carried out for 1 hour.

The following table shows the analysis of the precipitate and the operating efficiency:

TABLE 1

Example II

The procedure of example 1 was repeated except that 3 additional operations were added: sieving, magnetic iron removal and reuse of the final aqueous solution containing small amounts of lithium.

Screening is used to separate the metal powder from unwanted residues (plastics and metal parts) prior to leaching the metal powder. The iron small parts are then removed by magnetic force. These two operations added help reduce the amount of iron precipitation and the hydroxide filtration time.

The last aqueous solution containing a small amount of lithium is recycled back to the leaching step, not only meeting environmental standards and saving water, but also the remaining lithium that has not been carbonated will be recovered.

TABLE 2

Example III

In this embodiment, in order to further improve the efficiency of the leaching operation, the leaching operation is repeated.

By optimizingThe leaching parameters may increase the efficiency of the leaching operation. A reducing agent such as 10g/L aluminum (foil) or 4g/L manganese dioxide is used in place of some or all of the hydrogen peroxide. 1.6mL/g H was added ₂ O ₂ And 4g/L MnO ₂ Seems to be the most effective.

While the present disclosure has been described with particular reference to the illustrated embodiments, it will be appreciated that numerous modifications thereto may be devised by those skilled in the art. It should be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the application involving those features necessary to be within the skill of the art and having been set forth above and such departures from the present disclosure as come within the scope of the appended claims.

Claims

1. A method of recycling lithium ion batteries, comprising the steps of:

a) Shredding the lithium ion battery, immersing the residue in an organic solvent to safely discharge the battery and produce shredded battery residue and a liquid comprising an organic compound and lithium hexafluorophosphate;

b) Feeding the shredded battery residue into a dryer to produce a gaseous organic phase and a dried battery residue;

c) Feeding dried battery residue comprising magnetic battery residue and non-magnetic battery residue to a magnetic separator, removing magnetic particles from the dried battery residue;

d) Milling the non-magnetic battery residue to produce a particle size distribution comprising: an upper range comprising plastic and middle and lower ranges comprising fine particles of aluminum, copper, metal and graphite;

e) Mixing the fine particles with an acid to produce a slurry and leaching the slurry to produce a leachate comprising metal sulfate and non-leachable materials;

f) Filtering the leachate to remove the non-leachable material from the leachate;

g) Feeding the leachate into a sulfide precipitation tank to remove ionic copper impurities from the leachate;

h) Neutralizing the leachate at a pH of 3.5 to 5 to remove remaining iron and aluminum from the leachate;

i) Mixing the leachate with an organic extraction solvent to produce an aqueous phase comprising lithium and an organic phase comprising cobalt, manganese and nickel;

j) Crystallizing sodium sulfate from the aqueous phase containing lithium to produce a liquid containing lithium and sodium sulfate crystals;

k) Adding sodium carbonate to the liquid and heating the sodium carbonate and the liquid to produce a lithium carbonate precipitate; and

l) drying and recovering lithium carbonate;

wherein the organic solvent is at a temperature of less than 40 ℃.

2. The method of claim 1, wherein the organic solvent is an aliphatic carbonate.

3. The method of claim 1 or 2, wherein the lithium ion battery is shredded to a particle size of 5-10 millimeters.

4. The method of claim 1 or 2, wherein the shredded battery residue is separated from the liquid by sieving or filtration.

5. The method of claim 1 or 2, further comprising evaporating the liquid of step a) in an evaporator to produce a condensate of the slurry and light organics.

6. The method of claim 5, comprising separating dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC) and Ethylene Carbonate (EC) from the condensate of light organics.

7. The process of claim 5, further comprising recovering the condensate of light organics as the organic solvent in step a).

8. The method of claim 5, wherein the slurry is combusted at a temperature of 500 ℃ to produce a slurry comprising hydrofluoric acid HF and phosphorus pentoxide p ₂ O ₅ Is a combustion gas of (a) a combustion gas of (b).

9. The process of claim 8 wherein HF is further removed in a dry scrubber and P is neutralized in a wet scrubber ₂ O ₅ Sodium phosphate (Na) ₃ PO ₄ )。

10. The method of claim 1 or 2, wherein the shredded battery residue is dried at a temperature of 200-300 ℃.

11. The method of claim 1 or 2, wherein the non-magnetic battery residue is ground in a hammer mill or impact crusher.

12. The method of claim 1 or 2, further comprising extracting aluminum and copper from the milled non-magnetic cell with an eddy current separator.

13. The method of claim 12, wherein aluminum and copper are further separated.

14. The method of claim 1 or 2, wherein the fine particles are mixed with sulfuric acid and water to produce a metal oxide slurry having a solids concentration of 75 to 125kg solids per cubic meter of acid solution.

15. The method of claim 1 or 2, further comprising adding a reducing agent to the metal oxide slurry for leaching.

16. The method of claim 15, wherein the reducing agent is hydrogen peroxide (H ₂ O ₂ ) Manganese oxide (MnO) ₂ ) At least one of aluminum (Al) and combinations thereof.

17. The method of claim 1 or 2, further comprising filtering graphite from the leachate and purifying it in a furnace.

18. The method of claim 17, wherein the oven is operated at a temperature of 200 to 800 ℃.

19. The method of claim 1 or 2, further comprising precipitating ionic copper impurities by precipitation with sulfur ions.

20. The process according to claim 1 or 2, further comprising mixing the leachate in step j) and the organic extraction solvent in a diluent.

21. The process according to claim 1 or 2, further comprising washing and stripping the organic phase from step i) to extract cobalt and manganese.

22. The method of claim 21, wherein cobalt and manganese are separated by electrolytic deposition.

23. The method of claim 1 or 2, further comprising increasing the pH of the aqueous phase to a pH of 10 to 12 to precipitate nickel from the aqueous phase.

24. The method of claim 1 or 2, further comprising electrolyzing the sodium sulfate crystals to produce sulfuric acid and sodium hydroxide.